In recent years the use of shipping containers has virtually revolutionized the freight handling industry, especially for international shipments, because of the convenience and economic advantages accruing from the use of weatherproof containers of rectangular shape which are capable of storing a number of unit items, whether packages or bulk material, while confining and protecting the contents from loss or damage during transport as a unitary load that can be separated from the means of transport and transshipped without rehandling the contents.
In this connection, standardized containers (I. S. O. standard) and standardized handling equipment have been developed concurrently to reap the maximum benefit from this development. At this date, there is a world-wide body of carriers, shippers, leasing companies, repair facilities, and manufacturers who are involved in international intermodal transportation systems and who have an economic stake in assuring that the containers transported or serviced by them should be in compliance with established standards. These standards are based upon a container of 40-foot length, and provide for use of shorter modules which can be arranged to occupy the space provided for a 40-foot container in the hold of a ship or other intermodal transport.
General economic considerations as well as the increased use of modular containers now makes it even more desireable to reduce the actual manipulation of the shorter modules by releasably coupling two or more modules together to form a structurally stable assembly that can be handled with standard equipment designed for use with the 40-foot container.
As is well known in the art, standard shipping containers or the type described have at each corner a corner fitting in which there is an orifice in each exterior face, each orifice opening into a common recess within the corner fitting.
Existing devices of the prior art for horizontal coupling of containers at their corner fittings are not completely satisfactory in that they generally lack any means for gathering the containers together during the act of coupling, are incapable of being selectively fastened to or disconnected from either one or both of two containers, and cannot be used at the top corner fitting as well as at the bottom corner fitting.